/* NXT BOOK — product stylesheet (app + landing). Loaded only on NXT BOOK pages, after the shared
   layers. Personality: editorial, literary, premium — paper and ink. Visual language: typographic
   covers drawn from each book (serif type over line-art patterns), manuscript pages with real
   margins, hairline rules, a status stepper drawn as shapes, EAN-13 barcodes from recorded ISBNs.
   Black, white and greys only (tokens); the serif is the reader's system book face. */

@layer product {
  .p-book, .bk-page, .bkl { --bk-serif: 'Iowan Old Style', 'Palatino Linotype', Palatino, 'Book Antiqua', Georgia, 'Times New Roman', serif; }

  /* ---------- Covers ---------- */
  .bcover { position: relative; display: grid; aspect-ratio: 2 / 3; overflow: hidden; isolation: isolate; border-radius: 3px 6px 6px 3px; background: var(--c-surface); color: var(--c-text); box-shadow: inset 0 0 0 1px var(--c-border-strong), 0 1px 2px rgb(0 0 0 / 0.08), 0 10px 24px -12px rgb(0 0 0 / 0.35); container-type: inline-size; }
  .bcover.is-ink { background: #0A0A0A; color: #F5F5F5; box-shadow: 0 1px 2px rgb(0 0 0 / 0.2), 0 10px 24px -12px rgb(0 0 0 / 0.5); }
  .bcover.is-grey { background: #3D3D3D; color: #FFFFFF; }
  .bc-art { position: absolute; inset: 0; width: 100%; height: 100%; z-index: -1; }
  .bc-art path { fill: none; stroke: currentColor; stroke-width: 0.8; opacity: 0.22; }
  .bc-margin .bc-art path { opacity: 0.5; }
  .bc-spine { position: absolute; inset: 0 auto 0 0; width: 7%; background: linear-gradient(90deg, rgb(0 0 0 / 0.18), rgb(255 255 255 / 0.06) 60%, transparent); pointer-events: none; }
  .bc-type { display: grid; align-content: space-between; gap: 6cqi; padding: 12cqi 10cqi 10cqi 14cqi; min-width: 0; }
  .bc-genre { font: 600 6cqi/1.2 var(--font-mono); letter-spacing: 0.14em; text-transform: uppercase; opacity: 0.75; }
  .bc-title { font: 600 15cqi/1.02 var(--bk-serif); letter-spacing: -0.01em; overflow-wrap: anywhere; align-self: center; }
  .bc-sub { font: italic 7cqi/1.25 var(--bk-serif); opacity: 0.8; margin-top: -3cqi; }
  .bc-author { font: 600 6.5cqi/1.2 var(--font-sans); letter-spacing: 0.12em; text-transform: uppercase; align-self: end; }
  .bc-sm { width: 72px; }
  .bc-md { width: 100%; }
  .bc-lg { width: 100%; max-width: 220px; }

  /* ---------- Frame: book section strip (phones and tablets) ---------- */
  .bk-strip { margin: calc(var(--s-2) * -1) 0 var(--s-6); }
  .bk-strip ul { list-style: none; margin: 0; padding: 0 0 2px; display: flex; gap: 6px; overflow-x: auto; scrollbar-width: none; }
  .bk-strip ul::-webkit-scrollbar { display: none; }
  .bk-strip li { margin: 0; flex: none; }
  .bk-strip a { display: inline-flex; align-items: center; min-height: 40px; padding: 0 var(--s-4); border-radius: var(--r-sm); border: 1px solid var(--c-border); background: var(--c-surface); color: var(--c-muted); font-size: var(--t-small); font-weight: 600; text-decoration: none; white-space: nowrap; }
  .bk-strip a[aria-current='page'] { color: var(--c-on-primary); background: var(--c-primary); border-color: var(--c-primary); }
  @media (min-width: 1024px) { .bk-strip { display: none; } }

  .bk-cols { display: grid; gap: var(--s-5); grid-template-columns: minmax(0, 1fr); margin-top: var(--s-5); }
  .bk-cols > .panel { margin: 0; }
  @media (min-width: 900px) { .bk-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
  .bk-clear { display: flex; gap: var(--s-2); align-items: center; margin: 0; font-weight: 600; }
  .bk-clear span { font-weight: 500; }
  .bk-attn .step-title { margin: 0; font-weight: 600; }
  .bk-attn p { margin: 2px 0 0; }
  .bk-plan { margin-top: var(--s-5); display: grid; gap: var(--s-3); }
  .bk-plan .h-xs { margin: 0; }
  .bk-bar { display: block; height: 4px; border-radius: 2px; background: var(--c-surface2); overflow: hidden; box-shadow: inset 0 0 0 1px var(--c-border); }
  .bk-bar i { display: block; height: 100%; background: var(--c-text); }
  .bk-bar.is-wide { height: 6px; max-width: 420px; margin-top: var(--s-3); }
  .rail-block + .rail-block { margin-top: var(--s-6); padding-top: var(--s-6); border-top: 1px solid var(--c-border); }
  .rail-title { font: 600 var(--t-h4)/1.3 var(--font-sans); margin: 0 0 var(--s-4); }
  .app-rail .form { max-width: none; gap: var(--s-4); }

  /* ---------- Desk (dashboard) ---------- */
  .bk-desk { display: grid; gap: 0; border: 1px solid var(--c-border); border-radius: var(--r-xl); background: var(--c-surface); overflow: hidden; box-shadow: var(--e-1); }
  .bk-desk-page { position: relative; padding: clamp(var(--s-6), 4vw, var(--s-10)); display: grid; gap: var(--s-3); align-content: start; background: repeating-linear-gradient(180deg, transparent 0 31px, color-mix(in srgb, var(--c-border) 60%, transparent) 31px 32px); background-position: 0 14px; }
  .bk-desk-page::before { content: ''; position: absolute; top: 0; bottom: 0; left: clamp(14px, 2.5vw, 28px); border-left: 1px solid var(--c-border-strong); opacity: 0.6; }
  .bk-desk-page .overline { margin: 0; }
  .bk-desk-page h2 { font: 600 clamp(1.75rem, 1.3rem + 1.8vw, 2.625rem)/1.08 var(--bk-serif); letter-spacing: -0.015em; }
  .bk-desk-page h2 a { color: var(--c-text); text-decoration: none; }
  .bk-desk-page h2 a:hover { text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 4px; }
  .bk-desk-in { margin: 0; color: var(--c-muted); font-size: var(--t-small); }
  .bk-desk-in em { font-family: var(--bk-serif); font-size: 1.05em; color: var(--c-text); }
  .bk-excerpt { margin: var(--s-2) 0 var(--s-3); padding: 0; border: 0; max-width: 62ch; }
  .bk-excerpt p { margin: 0; font: 400 1.125rem/2 var(--bk-serif); color: var(--c-text); }
  .bk-excerpt.is-blank { font-family: var(--bk-serif); font-style: italic; color: var(--c-muted); }
  .bk-caret { display: inline-block; width: 2px; height: 1.15em; margin-left: 3px; vertical-align: -0.2em; background: var(--c-text); }
  @media (prefers-reduced-motion: no-preference) { .bk-caret { animation: bk-blink 1.1s steps(1) infinite; } }
  @keyframes bk-blink { 50% { opacity: 0; } }
  .bk-desk-book { display: grid; grid-template-columns: 120px minmax(0, 1fr); gap: var(--s-5); align-items: center; padding: var(--s-6); border-top: 1px solid var(--c-border); background: var(--c-surface2); }
  .bk-desk-cover { display: block; text-decoration: none; transition: transform var(--d-base) var(--ease-out); }
  .bk-desk-cover:hover { transform: translateY(-3px) rotate(-1deg); }
  .bk-desk-goal { display: grid; gap: var(--s-3); justify-items: start; }
  .bk-desk-goal p { margin: 0; font-size: var(--t-small); color: var(--c-muted); }
  .bk-desk-goal strong { color: var(--c-text); font: 650 1.25rem/1 var(--font-display); }
  @media (min-width: 1100px) {
    .bk-desk { grid-template-columns: minmax(0, 1.7fr) minmax(260px, 0.8fr); }
    .bk-desk-book { grid-template-columns: minmax(0, 1fr); border-top: 0; border-left: 1px solid var(--c-border); align-content: center; justify-items: center; text-align: center; }
    .bk-desk-cover { width: 170px; }
    .bk-desk-goal { justify-items: center; }
  }

  .bk-sessions { position: relative; overflow: hidden; }
  .bk-sessions .heat-grid { --heat-cols: 7; max-width: 380px; font-size: var(--t-caption); }
  .bk-sessions .heat-row { white-space: nowrap; }
  .bk-sessions .heat { max-width: 380px; }
  .bk-recent { list-style: none; margin: 0; padding: 0; display: grid; }
  .bk-recent li { margin: 0; border-top: 1px solid var(--c-border); }
  .bk-recent li:first-child { border-top: 0; }
  .bk-recent a { display: grid; gap: 2px; padding: 10px 0; color: var(--c-text); text-decoration: none; }
  .bk-recent a:hover .bk-recent-t { text-decoration: underline; }
  .bk-recent-t { font: 600 1.0625rem/1.3 var(--bk-serif); }
  .bk-recent-m { font-size: var(--t-caption); color: var(--c-muted); }

  .bk-shelf-wrap { margin-top: var(--s-8); }
  .bk-shelf-wrap > .spread { margin-bottom: var(--s-5); }
  .bk-shelf-wrap h2 { font: 600 var(--t-h3)/1.3 var(--font-sans); }
  .bk-shelf { list-style: none; margin: 0; padding: var(--s-5) 0 0; display: grid; gap: var(--s-8) var(--s-5); grid-template-columns: repeat(auto-fill, minmax(min(100%, 150px), 1fr)); border-top: 2px solid var(--c-text); }
  .bk-shelf-item { margin: 0; display: grid; gap: var(--s-2); align-content: start; }
  .bk-shelf-link { display: grid; gap: var(--s-3); color: var(--c-text); text-decoration: none; }
  .bk-shelf-link .bcover { transition: transform var(--d-base) var(--ease-out), box-shadow var(--d-base) var(--ease-out); }
  .bk-shelf-link:hover .bcover { transform: translateY(-4px); }
  .bk-shelf-link:hover .bk-shelf-title { text-decoration: underline; }
  .bk-shelf-title { font: 600 1.0625rem/1.25 var(--bk-serif); overflow-wrap: anywhere; }
  .bk-shelf-meta { display: flex; flex-wrap: wrap; gap: 4px var(--s-2); align-items: center; margin: 0; font-size: var(--t-caption); color: var(--c-muted); }
  .bk-shelf-item p.small { margin: 0; }

  .bk-welcome { display: grid; gap: var(--s-8); align-items: center; padding: clamp(var(--s-6), 5vw, var(--s-12)); border: 1px solid var(--c-border); border-radius: var(--r-xl); background: var(--c-surface); margin-bottom: var(--s-5); }
  .bk-welcome-stack { width: 180px; justify-self: center; transform: rotate(-3deg); }
  .bk-welcome-copy { display: grid; gap: var(--s-3); }
  .bk-welcome-copy .overline { margin: 0; }
  .bk-welcome-copy h2 { font: 600 clamp(1.75rem, 1.3rem + 1.6vw, 2.5rem)/1.1 var(--bk-serif); }
  .bk-welcome-copy p { margin: 0; color: var(--c-muted); max-width: 60ch; }
  @media (min-width: 900px) { .bk-welcome { grid-template-columns: 240px minmax(0, 1fr); } }

  /* ---------- Status stepper ---------- */
  .bk-steps { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 4px 0; font-size: var(--t-caption); font-weight: 600; color: var(--c-muted); }
  .bk-steps li { display: inline-flex; align-items: center; gap: 6px; margin: 0; }
  .bk-steps li + li::before { content: ''; width: 18px; height: 0; border-top: 1px solid var(--c-border-strong); margin: 0 6px; }
  .bk-steps li.is-done + li::before { border-top: 2px solid var(--c-text); }
  .bk-step-dot { width: 10px; height: 10px; border-radius: 50%; border: 1.5px solid var(--c-border-strong); background: var(--c-surface); }
  .bk-steps .is-done { color: var(--c-text); }
  .bk-steps .is-done .bk-step-dot { background: var(--c-text); border-color: var(--c-text); }
  .bk-steps .is-current { color: var(--c-text); }
  .bk-steps .is-current .bk-step-dot { width: 12px; height: 12px; border-radius: 2px; border: 2px solid var(--c-text); box-shadow: 0 0 0 3px var(--c-surface), 0 0 0 4px var(--c-text); }

  /* ---------- Book overview ---------- */
  .bk-hero { display: grid; gap: var(--s-6); align-items: center; margin-bottom: var(--s-5); padding: var(--s-6); border: 1px solid var(--c-border); border-radius: var(--r-xl); background: var(--c-surface); }
  .bk-hero-cover { width: 150px; max-width: 150px; justify-self: center; }
  .bk-hero-body { display: grid; gap: var(--s-5); min-width: 0; }
  .bk-facts { margin: 0; display: grid; gap: var(--s-4) var(--s-6); grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); }
  .bk-facts div { display: grid; gap: 2px; padding-left: var(--s-3); border-left: 1px solid var(--c-border-strong); }
  .bk-facts dt { font: 600 var(--t-overline)/1.3 var(--font-mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--c-muted); }
  .bk-facts dd { margin: 0; font: 650 1.5rem/1.15 var(--font-display); letter-spacing: -0.02em; }
  .bk-facts .bk-of { font-size: 0.875rem; color: var(--c-muted); font-weight: 500; letter-spacing: 0; }
  .bk-facts .bk-dd-note { font: 400 var(--t-caption)/1.3 var(--font-sans); color: var(--c-muted); letter-spacing: 0; }
  @media (min-width: 720px) { .bk-hero { grid-template-columns: 150px minmax(0, 1fr); } }

  .bk-toc-group { margin: var(--s-5) 0 0; padding-bottom: var(--s-2); border-bottom: 1px solid var(--c-text); font: 600 var(--t-overline)/1.3 var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; }
  .bk-toc .panel-head + .bk-toc-group { margin-top: 0; }
  .bk-toc-list { list-style: none; margin: 0; padding: 0; display: grid; }
  .bk-toc-row { display: grid; grid-template-columns: 52px minmax(0, 1fr) auto; grid-template-areas: 'n main move' 'n len move'; column-gap: var(--s-3); align-items: start; margin: 0; padding: var(--s-3) 0; border-bottom: 1px dotted var(--c-border-strong); }
  .bk-toc-n { grid-area: n; font: 600 1rem/1.5 var(--bk-serif); color: var(--c-muted); text-transform: uppercase; letter-spacing: 0.04em; overflow-wrap: anywhere; }
  .bk-toc-n.is-num { font: 600 1.5rem/1 var(--bk-serif); color: var(--c-text); text-transform: none; letter-spacing: 0; padding-top: 2px; }
  .k-part .bk-toc-n { color: var(--c-text); font-weight: 700; }
  .bk-toc-main { grid-area: main; min-width: 0; }
  .bk-toc-title { font: 600 1.125rem/1.3 var(--bk-serif); color: var(--c-text); text-decoration: none; overflow-wrap: anywhere; }
  .bk-toc-title:hover { text-decoration: underline; text-underline-offset: 3px; }
  .bk-toc-ex { margin: 2px 0 0; font: italic 400 0.9375rem/1.45 var(--bk-serif); color: var(--c-muted); display: -webkit-box; -webkit-line-clamp: 2; line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
  .bk-blank { font-style: normal; font-family: var(--font-sans); font-size: var(--t-caption); padding: 1px 6px; border: 1px dashed var(--c-border-strong); border-radius: var(--r-xs); }
  .bk-toc-len { grid-area: len; display: flex; gap: var(--s-2); align-items: center; margin-top: 6px; font-size: var(--t-caption); color: var(--c-muted); }
  .bk-len { display: block; width: 120px; height: 3px; background: var(--c-surface2); box-shadow: inset 0 0 0 1px var(--c-border); }
  .bk-len i { display: block; height: 100%; background: var(--c-text); }
  .bk-toc-upd { display: none; }
  .bk-toc-move { grid-area: move; display: flex; gap: 2px; }
  .bk-toc-move form { margin: 0; }
  .bk-move-gap { width: 40px; }
  .k-part { background: repeating-linear-gradient(135deg, transparent 0 6px, color-mix(in srgb, var(--c-border) 50%, transparent) 6px 7px); }
  @media (min-width: 900px) {
    .bk-toc-row { grid-template-columns: 56px minmax(0, 1fr) 150px 110px auto; grid-template-areas: 'n main len upd move'; align-items: center; }
    .bk-toc-len { margin: 0; flex-direction: column; align-items: flex-end; gap: 4px; }
    .bk-toc-upd { display: block; grid-area: upd; text-align: right; }
  }
  .bk-reorder { margin-top: var(--s-5); }
  .bk-reorder > summary { font-weight: 600; font-size: var(--t-small); padding: var(--s-2) 0; }
  .bk-reorder-grid { display: grid; gap: var(--s-3) var(--s-4); grid-template-columns: repeat(auto-fill, minmax(min(100%, 220px), 1fr)); }
  .bk-rail-ring { display: flex; gap: var(--s-3); align-items: center; }
  .bk-rail-ring p { margin: 0; }
  .bk-next-steps { list-style: none; margin: 0 0 var(--s-4); padding: 0; display: grid; gap: var(--s-4); }
  .bk-next-steps li { display: grid; grid-template-columns: 20px minmax(0, 1fr); gap: var(--s-3); margin: 0; font-size: var(--t-small); color: var(--c-muted); }
  .bk-next-steps strong { color: var(--c-text); }

  /* ---------- Editor ---------- */
  .bk-editor { display: grid; gap: 0; }
  .bk-ed-bar { position: sticky; top: calc(var(--layout-header) + var(--s-2)); z-index: var(--z-raised); display: flex; flex-wrap: wrap; justify-content: space-between; gap: var(--s-2) var(--s-4); align-items: center; padding: 8px 8px 8px var(--s-4); border: 1px solid var(--c-border); border-radius: var(--r-md) var(--r-md) 0 0; background: color-mix(in srgb, var(--c-surface) 92%, transparent); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); }
  .bk-ed-status { display: flex; flex-wrap: wrap; gap: 2px var(--s-3); margin: 0; color: var(--c-muted); }
  .bk-ed-count { color: var(--c-text); font-weight: 650; }
  [data-save-status] { font-weight: 600; color: var(--c-text); }
  .bk-ed-actions { display: flex; gap: var(--s-3); align-items: center; }
  .bk-ed-kbd kbd { font: 500 11px/1 var(--font-mono); padding: 3px 5px; border: 1px solid var(--c-border-strong); border-bottom-width: 2px; border-radius: 4px; }
  @media (max-width: 639px) { .bk-ed-kbd, .bk-ed-book { display: none; } }
  .bk-sheet { padding: clamp(var(--s-5), 5vw, var(--s-16)) clamp(var(--s-4), 6vw, var(--s-20)); border: 1px solid var(--c-border); border-top: 0; border-radius: 0 0 var(--r-md) var(--r-md); background: var(--c-surface); box-shadow: 0 1px 0 var(--c-border), 0 18px 40px -28px rgb(0 0 0 / 0.35); }
  .bk-sheet > * { max-width: 68ch; margin-inline: auto; }
  .bk-sheet-meta { display: flex; justify-content: flex-end; }
  .bk-sheet-meta .field { width: min(100%, 300px); }
  .bk-sheet-meta label { font: 600 var(--t-overline)/1.3 var(--font-mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--c-muted); }
  .bk-title-field { margin-top: var(--s-6); }
  .bk-title-field label { font: 600 var(--t-overline)/1.3 var(--font-mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--c-muted); }
  .bk-title-field input { font: 600 clamp(1.75rem, 1.3rem + 1.8vw, 2.5rem)/1.15 var(--bk-serif); letter-spacing: -0.01em; border: 0; border-bottom: 1px solid var(--c-border-strong); border-radius: 0; padding: 6px 0 10px; background: transparent; box-shadow: none; height: auto; }
  .bk-title-field input:focus-visible { border-bottom-color: var(--c-text); }
  .bk-body-field { margin-top: var(--s-6); }
  .book-text { min-height: 62vh; width: 100%; font: 400 1.1875rem/1.85 var(--bk-serif); color: var(--c-text); border: 0; padding: 0; background: transparent; box-shadow: none; resize: vertical; }
  .book-text:focus-visible { box-shadow: none; outline: none; }
  .bk-sheet:has(.book-text:focus-visible) { box-shadow: 0 0 0 2px var(--c-focus), 0 18px 40px -28px rgb(0 0 0 / 0.35); }
  .bk-ed-foot { display: flex; flex-wrap: wrap; justify-content: space-between; gap: var(--s-3); align-items: center; margin-top: var(--s-4); }
  .bk-help > summary { display: inline-flex; gap: 6px; align-items: center; font-size: var(--t-small); font-weight: 600; padding: var(--s-2) 0; }
  .bk-help ul { margin: var(--s-2) 0 0; font-size: var(--t-small); }
  .bk-preview-panel { margin-top: var(--s-5); }
  .bk-preview-panel > summary { font-weight: 600; }
  .bk-typeset { max-width: 62ch; margin: var(--s-5) auto 0; font: 400 1.0625rem/1.7 var(--bk-serif); }
  .bk-typeset.is-justified p { text-align: justify; hyphens: auto; }
  .book-preview p { margin: 0; text-indent: 1.5em; }
  .book-preview p.first, .book-preview p.scene-break, .book-preview blockquote p { text-indent: 0; }
  .book-preview p.scene-break { text-align: center; margin: var(--s-3) 0; letter-spacing: 0.3em; }
  .book-preview blockquote { margin: var(--s-3) var(--s-6); }
  .bk-outline { list-style: none; margin: 0 0 var(--s-4); padding: 0; display: grid; max-height: 46vh; overflow-y: auto; }
  .bk-outline li { margin: 0; }
  .bk-outline a { display: grid; grid-template-columns: 22px minmax(0, 1fr) auto; gap: var(--s-2); align-items: baseline; padding: 6px 8px; border-radius: var(--r-sm); color: var(--c-text); text-decoration: none; font-size: var(--t-small); }
  .bk-outline a:hover { background: var(--c-surface2); }
  .bk-outline a[aria-current='page'] { background: var(--c-primary); color: var(--c-on-primary); }
  .bk-outline-n { font: 600 var(--t-caption)/1 var(--bk-serif); }
  .bk-outline-t { font-family: var(--bk-serif); font-size: 0.9375rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .bk-outline-w { font-size: var(--t-caption); opacity: 0.7; }
  .bk-rail-goal { margin-top: var(--s-2); }

  /* ---------- Versions & diff ---------- */
  .bk-vers { list-style: none; margin: 0; padding: 0; display: grid; position: relative; }
  .bk-vers::before { content: ''; position: absolute; left: 6px; top: 14px; bottom: 14px; border-left: 1px solid var(--c-border-strong); }
  .bk-vers li { position: relative; display: grid; grid-template-columns: 14px minmax(0, 1fr) auto; gap: var(--s-4); align-items: center; margin: 0; padding: var(--s-3) 0; }
  .bk-vers-dot { width: 13px; height: 13px; border-radius: 50%; border: 2px solid var(--c-text); background: var(--c-surface); z-index: 1; }
  .bk-vers li.is-latest .bk-vers-dot { background: var(--c-text); }
  .bk-vers li.n-autosave .bk-vers-dot { border-style: dashed; }
  .bk-vers li.n-before_restore .bk-vers-dot { border-radius: 2px; }
  .bk-vers-main p { margin: 0; }
  .bk-diff-stats { display: flex; flex-wrap: wrap; gap: var(--s-2) var(--s-5); align-items: baseline; margin: 0 0 var(--s-4); }
  .bk-ds-add, .bk-ds-del { display: inline-flex; gap: 6px; align-items: baseline; padding: 2px 10px; border-radius: var(--r-xs); font-size: var(--t-small); }
  .bk-ds-add { border: 1px solid var(--c-text); }
  .bk-ds-del { border: 1px dashed var(--c-border-strong); }
  .book-diff { font: 400 var(--t-small)/1.6 var(--font-mono); margin: 0; padding: var(--s-3) 0; border: 1px solid var(--c-border); border-radius: var(--r-md); background: var(--c-surface2); overflow-x: auto; }
  .book-diff span { display: block; padding: 1px var(--s-4); }
  .book-diff-add { background: var(--c-surface); box-shadow: inset 3px 0 0 var(--c-text); font-weight: 600; }
  .book-diff-del { color: var(--c-muted); text-decoration: line-through; background: repeating-linear-gradient(135deg, transparent 0 6px, color-mix(in srgb, var(--c-border-strong) 35%, transparent) 6px 7px); box-shadow: inset 3px 0 0 var(--c-border-strong); }
  .book-diff-skip { color: var(--c-muted); font-style: italic; text-align: center; }
  .bk-restore { display: flex; flex-wrap: wrap; gap: var(--s-4); justify-content: space-between; align-items: center; }
  .bk-restore h2 { margin-bottom: var(--s-1); }
  .bk-restore p { margin: 0; max-width: 60ch; }
  .bk-version-text { font: 400 1rem/1.7 var(--bk-serif); }

  /* ---------- Design & details: live page preview (pure CSS, reacts to the form with :has) ---------- */
  .bk-design-grid { display: grid; gap: var(--s-8); align-items: start; }
  @media (min-width: 1100px) { .bk-design-grid { grid-template-columns: minmax(0, 1fr) minmax(280px, 0.85fr); } }
  .bk-fs { border: 0; padding: 0; margin: 0 0 var(--s-2); display: grid; gap: var(--s-4); }
  .bk-fs legend { font: 600 var(--t-overline)/1.3 var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--c-muted); padding: 0 0 var(--s-2); margin-bottom: var(--s-2); border-bottom: 1px solid var(--c-border); width: 100%; }
  .bk-pv { margin: 0; position: sticky; top: calc(var(--layout-header) + var(--s-4)); display: grid; gap: var(--s-3); }
  .bk-pv-page { --pv-size: 11; --pv-lh: 1.35; position: relative; aspect-ratio: 6 / 9; overflow: hidden; padding: 11% 12% 14%; background: #FFFFFF; color: #111111; border-radius: 2px; box-shadow: 0 0 0 1px var(--c-border-strong), 0 20px 40px -24px rgb(0 0 0 / 0.45); font-family: var(--bk-serif); font-size: calc(var(--pv-size) * 0.0848rem); line-height: var(--pv-lh); container-type: inline-size; transition: aspect-ratio var(--d-slow) var(--ease-out), font-size var(--d-base); }
  .bk-pv-label { margin: 6% 0 1%; text-align: center; font: 600 0.7em/1.2 var(--font-sans); letter-spacing: 0.22em; text-transform: uppercase; }
  .bk-pv-label span { display: none; }
  .bk-pv-title { margin: 0 0 9%; text-align: center; font-size: 1.6em; line-height: 1.15; }
  .bk-pv-text p { margin: 0; text-indent: 1.4em; }
  .bk-pv-text p.first { text-indent: 0; }
  .bk-pv-text .scene-break { display: none; }
  .bk-pv-break { text-align: center !important; text-indent: 0 !important; margin: 0.6em 0 !important; letter-spacing: 0.2em; }
  .bk-pv-break span { display: none; }
  .bk-pv-folio { position: absolute; left: 0; right: 0; bottom: 5%; margin: 0; text-align: center; font-size: 0.75em; display: none; }
  .bk-design:has(select[name='trim'] option[value='5x8']:checked) .bk-pv-page { aspect-ratio: 5 / 8; }
  .bk-design:has(select[name='trim'] option[value='5.25x8']:checked) .bk-pv-page { aspect-ratio: 5.25 / 8; }
  .bk-design:has(select[name='trim'] option[value='5.5x8.5']:checked) .bk-pv-page { aspect-ratio: 5.5 / 8.5; }
  .bk-design:has(select[name='trim'] option[value='a5']:checked) .bk-pv-page { aspect-ratio: 148 / 210; }
  .bk-design:has(select[name='font_size'] option[value='9']:checked) .bk-pv-page { --pv-size: 9; }
  .bk-design:has(select[name='font_size'] option[value='10']:checked) .bk-pv-page { --pv-size: 10; }
  .bk-design:has(select[name='font_size'] option[value='10.5']:checked) .bk-pv-page { --pv-size: 10.5; }
  .bk-design:has(select[name='font_size'] option[value='11.5']:checked) .bk-pv-page { --pv-size: 11.5; }
  .bk-design:has(select[name='font_size'] option[value='12']:checked) .bk-pv-page { --pv-size: 12; }
  .bk-design:has(select[name='font_size'] option[value='13']:checked) .bk-pv-page { --pv-size: 13; }
  .bk-design:has(select[name='font_size'] option[value='14']:checked) .bk-pv-page { --pv-size: 14; }
  .bk-design:has(select[name='line_spacing'] option[value='1.15']:checked) .bk-pv-page { --pv-lh: 1.15; }
  .bk-design:has(select[name='line_spacing'] option[value='1.25']:checked) .bk-pv-page { --pv-lh: 1.25; }
  .bk-design:has(select[name='line_spacing'] option[value='1.5']:checked) .bk-pv-page { --pv-lh: 1.5; }
  .bk-design:has(select[name='line_spacing'] option[value='1.75']:checked) .bk-pv-page { --pv-lh: 1.75; }
  .bk-design:has(select[name='line_spacing'] option[value='2']:checked) .bk-pv-page { --pv-lh: 2; }
  .bk-design:has(select[name='pdf_font'] option[value='helvetica']:checked) .bk-pv-page { font-family: Helvetica, Arial, var(--font-sans); }
  .bk-design:has(input[name='justify']:checked) .bk-pv-text p { text-align: justify; hyphens: auto; }
  .bk-design:has(input[name='page_numbers']:checked) .bk-pv-folio { display: block; }
  .bk-design:has(input[name='drop_caps']:checked) .bk-pv-text p.first::first-letter { float: left; font-size: 3.3em; line-height: 0.82; padding: 0.06em 0.08em 0 0; }
  .bk-design:has(select[name='chapter_style'] option[value='number_title']:checked) .bk-pv-label .cs-number_title,
  .bk-design:has(select[name='chapter_style'] option[value='number']:checked) .bk-pv-label .cs-number,
  .bk-design:has(select[name='chapter_style'] option[value='word_title']:checked) .bk-pv-label .cs-word_title { display: inline; }
  .bk-design:has(select[name='chapter_style'] option[value='number']:checked) .bk-pv-title { display: none; }
  .bk-design:has(select[name='chapter_style'] option[value='number']:checked) .bk-pv-label { margin-bottom: 9%; }
  .bk-design:has(select[name='chapter_style'] option[value='title']:checked) .bk-pv-label { visibility: hidden; }
  .bk-design:has(select[name='scene_break'] option[value='* * *']:checked) .sb-0,
  .bk-design:has(select[name='scene_break'] option[value='⁂']:checked) .sb-1,
  .bk-design:has(select[name='scene_break'] option[value='#']:checked) .sb-2,
  .bk-design:has(select[name='scene_break'] option[value='~']:checked) .sb-3,
  .bk-design:has(select[name='scene_break'] option[value='• • •']:checked) .sb-4 { display: inline; }
  @media (prefers-reduced-motion: reduce) { .bk-pv-page { transition: none; } }

  /* ---------- Metadata & ISBNs ---------- */
  .bk-formats { list-style: none; margin: 0 0 var(--s-6); padding: 0; display: grid; gap: var(--s-3); grid-template-columns: repeat(auto-fill, minmax(min(100%, 250px), 1fr)); }
  .bk-format { display: grid; gap: var(--s-3); align-content: start; margin: 0; padding: var(--s-4); border: 1px solid var(--c-border-strong); border-radius: var(--r-md); background: var(--c-surface); }
  .bk-format.is-missing { border-style: dashed; }
  .bk-format-head { display: flex; justify-content: space-between; align-items: center; gap: var(--s-2); }
  .bk-format-head form { margin: 0; }
  .bk-format-name { margin: 0; font: 600 1.125rem/1.2 var(--bk-serif); }
  .bk-isbn { display: grid; gap: 4px; }
  .bk-isbn p { margin: 0; }
  .bk-isbn code { font-size: var(--t-small); font-weight: 600; background: none; padding: 0; }
  .bk-isbn-k { font: 600 var(--t-overline)/1 var(--font-mono); letter-spacing: 0.08em; color: var(--c-muted); }
  .bk-ean { width: 160px; height: auto; padding: 8px; background: #FFFFFF; border-radius: 2px; box-shadow: inset 0 0 0 1px var(--c-border); }
  .bk-ean rect { fill: #000000; }
  .bk-isbn-none { display: flex; gap: 6px; align-items: center; margin: 0; font-size: var(--t-small); font-weight: 600; padding: 6px 10px; border-left: 3px solid var(--c-text); background: repeating-linear-gradient(135deg, transparent 0 6px, color-mix(in srgb, var(--c-border-strong) 35%, transparent) 6px 7px); }
  .bk-format-form { padding-top: var(--s-5); border-top: 1px solid var(--c-border); }
  .bk-listing { display: grid; grid-template-columns: 72px minmax(0, 1fr); gap: var(--s-3); align-items: start; margin-bottom: var(--s-3); }
  .bk-listing p { margin: 0; }
  .bk-listing-t { font: 600 1.125rem/1.2 var(--bk-serif); }
  .bk-listing-d { margin: 0 0 var(--s-3); font: 400 0.9375rem/1.6 var(--bk-serif); white-space: pre-line; }
  .bk-chips, .bk-cats { list-style: none; margin: 0 0 var(--s-3); padding: 0; display: flex; flex-wrap: wrap; gap: 6px; }
  .bk-chips li { margin: 0; padding: 2px 8px; border: 1px solid var(--c-border-strong); border-radius: var(--r-xs); font-size: var(--t-caption); }
  .bk-cats { display: grid; gap: 2px; }
  .bk-cats li { margin: 0; font: 500 var(--t-caption)/1.4 var(--font-mono); color: var(--c-muted); }

  /* ---------- Publishing checklist ---------- */
  .bk-chk-hero { display: flex; flex-wrap: wrap; gap: var(--s-6); align-items: center; margin-bottom: var(--s-5); padding: var(--s-6); border: 1px solid var(--c-border); border-radius: var(--r-xl); background: var(--c-surface); }
  .bk-chk-hero h2 { font: 600 clamp(1.5rem, 1.2rem + 1vw, 2rem)/1.1 var(--bk-serif); }
  .bk-chk-hero > div { flex: 1 1 260px; }
  .bk-chk-hero p { margin: var(--s-2) 0 0; }
  .bk-chk-hero .ring-text { font-size: 1rem; }
  .bk-stages { display: grid; gap: var(--s-4); grid-template-columns: repeat(auto-fit, minmax(min(100%, 320px), 1fr)); align-items: start; }
  .bk-stages > .panel { margin: 0; }
  .bk-stage-head { display: flex; justify-content: space-between; align-items: baseline; gap: var(--s-2); }
  .bk-stage-head h2 { font: 600 1.25rem/1.2 var(--bk-serif); }
  .bk-stage > p { margin: 2px 0 var(--s-3); }
  .bk-chk-list { list-style: none; margin: 0; padding: 0; display: grid; }
  .bk-chk { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; margin: 0; padding: 2px 0; border-top: 1px solid var(--c-border); }
  .bk-chk:first-child { border-top: 0; }
  .bk-chk > form:first-child { margin: 0; }
  .bk-chk-box { display: grid; grid-template-columns: 22px minmax(0, 1fr); gap: var(--s-3); align-items: center; width: 100%; min-height: 44px; padding: 6px 0; border: 0; background: none; color: var(--c-text); font: inherit; text-align: left; cursor: pointer; }
  .bk-chk-mark { display: grid; place-items: center; width: 22px; height: 22px; border-radius: var(--r-xs); border: 2px solid var(--c-border-strong); background: var(--c-surface); }
  .bk-chk-box:hover .bk-chk-mark { border-color: var(--c-text); }
  .bk-chk.is-done .bk-chk-mark { background: var(--c-text); border-color: var(--c-text); color: var(--c-surface); }
  .bk-chk.is-done .bk-chk-label { color: var(--c-muted); text-decoration: line-through; text-decoration-color: color-mix(in srgb, var(--c-muted) 60%, transparent); }
  .bk-chk-hint { grid-column: 1; margin: -4px 0 6px 34px; }
  .bk-chk-del { grid-column: 2; grid-row: 1; margin: 0; }
  .bk-chk-add .field { max-width: 520px; }
  .bk-chk-add .btn, .bk-format-form .btn { justify-self: start; }
  .bk-stages + .panel { margin-top: var(--s-5); }
  .bk-sheet-meta { justify-content: flex-start !important; }

  /* ---------- Export ---------- */
  .bk-export-lede { margin: 0 0 var(--s-5); color: var(--c-muted); max-width: 70ch; }
  .bk-exports { list-style: none; margin: 0 0 var(--s-5); padding: 0; display: grid; gap: var(--s-4); grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr)); }
  .bk-export { display: grid; gap: var(--s-3); align-content: start; grid-template-rows: auto auto auto 1fr auto; margin: 0; padding: var(--s-6); border: 1px solid var(--c-border); border-radius: var(--r-lg); background: var(--c-surface); }
  .bk-export.is-locked { border-style: dashed; background: transparent; }
  .bk-export-art { width: 56px; height: 56px; }
  .bk-export-art path { fill: none; stroke: var(--c-text); stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; }
  .bk-export h2 { font: 600 1.375rem/1.2 var(--bk-serif); display: flex; gap: var(--s-2); align-items: baseline; }
  .bk-export-ext { font: 500 var(--t-caption)/1 var(--font-mono); color: var(--c-muted); }
  .bk-export > p { margin: 0; }
  .bk-export-facts { list-style: none; margin: 0; padding: var(--s-3) 0 0; border-top: 1px dotted var(--c-border-strong); display: grid; gap: 4px; font-size: var(--t-caption); color: var(--c-muted); }
  .bk-export-facts li { margin: 0; }
  .bk-export-lock { display: flex; gap: 6px; align-items: flex-start; margin: 0; font-size: var(--t-small); }

  /* ---------- Landing (/nxt-book) ---------- */
  .bkl-hero { position: relative; overflow: hidden; isolation: isolate; padding: clamp(48px, 7vw, 104px) 0 clamp(40px, 5vw, 72px); background: var(--c-bg); border-bottom: 1px solid var(--c-border); }
  .bkl-hero::before { content: ''; position: absolute; inset: 0; z-index: -1; background: repeating-linear-gradient(180deg, transparent 0 39px, color-mix(in srgb, var(--c-border) 70%, transparent) 39px 40px); mask-image: linear-gradient(90deg, transparent, #000 30%, #000 70%, transparent); -webkit-mask-image: linear-gradient(90deg, transparent, #000 30%, #000 70%, transparent); opacity: 0.6; }
  .bkl-hero-grid { display: grid; gap: clamp(var(--s-8), 5vw, var(--s-16)); align-items: center; }
  @media (min-width: 1100px) { .bkl-hero-grid { grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.05fr); } }
  .bkl-hero-copy { display: grid; gap: var(--s-5); }
  .bkl-id { display: flex; gap: var(--s-3); align-items: center; margin: 0; }
  .bkl-name { font: 650 1.25rem/1 var(--font-display); letter-spacing: 0.02em; }
  .bkl-hero h1 { font: 500 clamp(2.75rem, 1.5rem + 5vw, 5.75rem)/0.98 var(--bk-serif); letter-spacing: -0.025em; }
  .bkl-hero h1 em { font-style: italic; }
  .bkl-hero .lede { margin: 0; max-width: 56ch; }
  .bkl-facts { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: var(--s-2) var(--s-5); font-size: var(--t-small); color: var(--c-muted); }
  .bkl-facts li { display: inline-flex; gap: 6px; align-items: center; margin: 0; }
  .bkl-hero-preview { min-width: 0; }
  .bkl-hero-preview .tab-panel { min-height: 400px; }
  .bkl-pv-write { display: grid; gap: 0; min-width: 0; }
  .bkl-pv-write .bk-sheet { min-width: 0; }
  .bkl-pv-write .bk-ed-bar { position: static; border-radius: var(--r-md) var(--r-md) 0 0; }
  .bkl-pv-write .bk-sheet { padding: var(--s-6) var(--s-6) var(--s-8); }
  .bkl-pv-title { margin: 0 0 var(--s-4); font: 600 1.75rem/1.15 var(--bk-serif); border-bottom: 1px solid var(--c-border-strong); padding-bottom: 8px; }
  .bkl-typed p { margin: 0; text-indent: 1.4em; font: 400 1.0625rem/1.8 var(--bk-serif); }
  .bkl-typed p:first-child { text-indent: 0; }
  .bkl-typed .bkl-type-line { display: inline; }
  @media (prefers-reduced-motion: no-preference) {
    .bkl-typed .bkl-type-last { animation: bkl-type 2.4s var(--ease-out) 0.5s both; }
  }
  @keyframes bkl-type { from { opacity: 0; filter: blur(2px); } to { opacity: 1; filter: none; } }
  .bkl-pv-toc .bk-toc-row { padding: 10px 0; }
  .bkl-pv-design { display: grid; gap: var(--s-5); grid-template-columns: minmax(0, 1fr); align-items: start; }
  @media (min-width: 560px) { .bkl-pv-design { grid-template-columns: minmax(0, 1fr) 200px; } }
  .bkl-pv-design .bk-pv { position: static; }
  .bkl-pv-design .form { gap: var(--s-3); }
  .bkl-stack { position: relative; height: clamp(240px, 70vw, 340px); }
  .bkl-stack .bcover { position: absolute; width: min(180px, 38%); }
  .bkl-stack .bcover:nth-child(1) { left: 6%; top: 34px; transform: rotate(-7deg); }
  .bkl-stack .bcover:nth-child(2) { left: 32%; top: 6px; z-index: 2; transform: rotate(1.5deg); }
  .bkl-stack .bcover:nth-child(3) { left: 58%; top: 40px; transform: rotate(8deg); }
  @media (prefers-reduced-motion: no-preference) {
    .bkl-stack .bcover { transition: transform var(--d-slow) var(--ease-spring); }
    .bkl-stack:hover .bcover:nth-child(1) { transform: rotate(-11deg) translate(-12px, -4px); }
    .bkl-stack:hover .bcover:nth-child(3) { transform: rotate(12deg) translate(12px, -4px); }
  }
  .bkl-arc { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 200px), 1fr)); border-top: 2px solid var(--c-text); }
  .bkl-arc li { margin: 0; padding: var(--s-5) var(--s-5) var(--s-5) 0; display: grid; gap: var(--s-2); align-content: start; border-bottom: 1px solid var(--c-border); }
  .bkl-arc-n { font: italic 600 2.5rem/1 var(--bk-serif); }
  .bkl-arc h3 { font: 600 1.25rem/1.2 var(--bk-serif); }
  .bkl-arc p { margin: 0; color: var(--c-muted); font-size: var(--t-small); }
  .bkl-duo { display: grid; gap: clamp(var(--s-8), 5vw, var(--s-16)); align-items: center; }
  @media (min-width: 1024px) { .bkl-duo { grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); } .bkl-duo.is-reverse .bkl-duo-copy { order: 2; } }
  .bkl-duo-copy .section-head { margin-bottom: var(--s-6); }
  .bkl-list { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-3); }
  .bkl-list li { display: grid; grid-template-columns: 18px minmax(0, 1fr); gap: var(--s-3); margin: 0; }
  .bkl-list .i { margin-top: 3px; }
  .bkl-quote { margin: 0; padding: var(--s-6) 0 0; border-top: 1px solid var(--c-border); font: italic 400 clamp(1.25rem, 1rem + 1vw, 1.75rem)/1.4 var(--bk-serif); max-width: 40ch; }
  .bkl-honest { list-style: none; margin: 0; padding: 0; display: grid; gap: 1px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr)); background: var(--c-border); border: 1px solid var(--c-border); border-radius: var(--r-lg); overflow: hidden; }
  .bkl-honest li { margin: 0; display: grid; gap: var(--s-2); align-content: start; padding: var(--s-6); background: var(--c-surface); }
  .bkl-honest h3 { font: 600 1.125rem/1.25 var(--bk-serif); }
  .bkl-honest p { margin: 0; color: var(--c-muted); font-size: var(--t-small); }
  .bkl-cap { display: flex; gap: 6px; align-items: center; margin: var(--s-3) 0 0; color: var(--c-muted); }
}